﻿/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2016 Thomas Braun, Jens Klingen, Robin Krom
 * 
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on GitHub https://github.com/greenshot/greenshot
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 1 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using log4net;
using System.Text.RegularExpressions;
using System.Collections.Generic;

namespace GreenshotPlugin.Core {
	public static class StringExtensions {
		private static readonly ILog LOG = LogManager.GetLogger(typeof(StringExtensions));
		private const string RGBIV = "dlgjowejgogkklwj";
		private const string KEY = "lsjvkwhvwujkagfauguwcsjgu2wueuff";

		/// <summary>
		/// Format a string with the specified object
		/// </summary>
		/// <param name="format">String with formatting, like {name}</param>
		/// <param name="source">Object used for the formatting</param>
		/// <returns>Formatted string</returns>
		public static string FormatWith(this string format, object source) {
			return FormatWith(format, null, source);
		}

		/// <summary>
		/// Format the string "format" with the source
		/// </summary>
		/// <param name="format"></param>
		/// <param name="provider"></param>
		/// <param name="source">object with properties, if a property has the type IDictionary string,string it can used these parameters too</param>
		/// <returns>Formatted string</returns>
		public static string FormatWith(this string format, IFormatProvider provider, object source) {
			if (format == null) {
				throw new ArgumentNullException(nameof(format));
			}

			IDictionary<string, object> properties = new Dictionary<string, object>();
			foreach(var propertyInfo in  source.GetType().GetProperties()) {
				if (propertyInfo.CanRead && propertyInfo.CanWrite) {
					object value = propertyInfo.GetValue(source, null);
					if (propertyInfo.PropertyType != typeof(IDictionary<string, string>)) {
						properties.Add(propertyInfo.Name, value);
					} else {
						IDictionary<string, string> dictionary = (IDictionary<string, string>)value;
						foreach (var propertyKey in dictionary.Keys) {
							properties.Add(propertyKey, dictionary[propertyKey]);
						}
					}
				}
			}

			Regex r = new Regex(@"(?<start>\{)+(?<property>[\w\.\[\]]+)(?<format>:[^}]+)?(?<end>\})+", RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);

			List<object> values = new List<object>();
			string rewrittenFormat = r.Replace(format, delegate(Match m) {
				Group startGroup = m.Groups["start"];
				Group propertyGroup = m.Groups["property"];
				Group formatGroup = m.Groups["format"];
				Group endGroup = m.Groups["end"];

				object value;
				values.Add(properties.TryGetValue(propertyGroup.Value, out value) ? value : source);
				return new string('{', startGroup.Captures.Count) + (values.Count - 1) + formatGroup.Value + new string('}', endGroup.Captures.Count);
			});

			return string.Format(provider, rewrittenFormat, values.ToArray());
		}

		/// <summary>
		/// A simply rijndael aes encryption, can be used to store passwords
		/// </summary>
		/// <param name="clearText">the string to call upon</param>
		/// <returns>an encryped string in base64 form</returns>
		public static string Encrypt(this string clearText) {
			string returnValue = clearText;
			try {
				byte[] clearTextBytes = Encoding.ASCII.GetBytes(clearText);
				SymmetricAlgorithm rijn = SymmetricAlgorithm.Create();
	
				using (MemoryStream ms = new MemoryStream()) {
					byte[] rgbIV = Encoding.ASCII.GetBytes(RGBIV);
					byte[] key = Encoding.ASCII.GetBytes(KEY);
					using (CryptoStream cs = new CryptoStream(ms, rijn.CreateEncryptor(key, rgbIV), CryptoStreamMode.Write)) {
						cs.Write(clearTextBytes, 0, clearTextBytes.Length);
						cs.FlushFinalBlock();

						returnValue = Convert.ToBase64String(ms.ToArray());
					}
				}
			} catch (Exception ex) {
				LOG.ErrorFormat("Error encrypting, error: {0}", ex.Message);
			}
			return returnValue;
		}

		/// <summary>
		/// A simply rijndael aes decryption, can be used to store passwords
		/// </summary>
		/// <param name="encryptedText">a base64 encoded rijndael encrypted string</param>
		/// <returns>Decrypeted text</returns>
		public static string Decrypt(this string encryptedText) {
			string returnValue = encryptedText;
			try {
				byte[] encryptedTextBytes = Convert.FromBase64String(encryptedText);
				using (MemoryStream ms = new MemoryStream()) {
					SymmetricAlgorithm rijn = SymmetricAlgorithm.Create();
	
	
					byte[] rgbIV = Encoding.ASCII.GetBytes(RGBIV);
					byte[] key = Encoding.ASCII.GetBytes(KEY);

					using (CryptoStream cs = new CryptoStream(ms, rijn.CreateDecryptor(key, rgbIV), CryptoStreamMode.Write)) {
						cs.Write(encryptedTextBytes, 0, encryptedTextBytes.Length);
						cs.FlushFinalBlock();
						returnValue = Encoding.ASCII.GetString(ms.ToArray());
					}
	
				}
			} catch (Exception ex) {
				LOG.ErrorFormat("Error decrypting {0}, error: {1}", encryptedText, ex.Message);
			}

			return returnValue;
		}

		/// <summary>
		/// Read "streamextensions" :)
		/// </summary>
		/// <param name="input">Stream</param>
		/// <param name="output">Stream</param>
		public static void CopyTo(this Stream input, Stream output) {
			byte[] buffer = new byte[16 * 1024]; // Fairly arbitrary size
			int bytesRead;

			while ((bytesRead = input.Read(buffer, 0, buffer.Length)) > 0) {
				output.Write(buffer, 0, bytesRead);
			}
		}
	}
}
